A seed bank is a facility used to store seeds of various crops and wild plants, in an effort to maintain biodiversity. These structures can be found scattered all over the world, established by governments and organizations concerned about crop diversity. The Global Crop Diversity Trust proposed in 2007 that an Arctic seed bank be established, to preserve seeds of vital crops in safe bunker conditions in the event of catastrophic events. Many nations agree, because they are concerned about damage to global seed receptacles due to political and environmental developments.
Globally, approximately 150 crops make up the majority of the food grown and consumed by humans. These crops have numerous subtle variations which make the plants more drought tolerant, frost resistant, nutritionally valuable, or easy to harvest. Farmers tend to cultivate crops in a way which will increase desirable traits at the expense of variation, and many biologists are concerned about the diversity of global crops. A seed bank is established to save samples of crop variations, so that they do not disappear forever.
Biodiversity is important for crops for a number of reasons. The first is that a crop could be highly vulnerable if one variety was heavily cultivated. A disease which evolved to attack the crop could devastate stocks worldwide if farmers all grew the same variety. If a seed bank had not been established, the crop might actually disappear, because no new plants could be grown. Hybridizing also makes crops stronger, and farmers are encouraged to breed back to wild versions of a crop to increase its hardiness on the farm, or to cross it with a different variety.
In a seed bank, samples of all the variations on a crop are kept in cool conditions so that they do not sprout or become damaged. Periodically, the seeds are used to grow plants, which are used to produce fresh seeds for the bank to ensure that the seeds will be viable if they ever need to be used. In addition, cultures of plants which do not readily grow from seed are kept in case they are needed. This is especially important with “orphan crops” such as cassava and taro, which make up a huge part of people's diets in some part of the world. Damage to these crops could have a very serious impact which can be averted by a seed bank.
A seed bank also preserves important pieces of regional heritage, such as rare and unusual crop varieties which are not viable commercially. A growing number of crops are cultivated for size, ease of harvesting, and shipping ability, at the cost of biodiversity and taste. A seed receptacle preserves antique varieties of a crop, and many biodiversity organizations also encourage farmers to grow heritage and heirloom crops on parts of the farms so that they do not die out.